Femoral cut guide

ABSTRACT

The present disclosure provides a femoral cut guide for preparing a distal femur to receive a prosthetic femoral component of a knee implant. The prosthetic femoral component includes a central box. The femoral cut guide replicates the size and shape of the prosthetic femoral component, such that the femoral cut guide may serve as a trial or provisional component used to reduce and test the prepared knee joint before implanting the final prosthetic femoral component. The femoral cut guide includes a detachable box cut guide for preparing the distal femur to receive the central box of the prosthetic femoral component.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from U.S. Provisional PatentApplication Ser. No. 61/311,443, entitled “FEMORAL CUT GUIDE,” filedMar. 8, 2010, the disclosure of which is hereby expressly incorporatedby reference herein in its entirety.

BACKGROUND

1. Field of the Invention

The present invention relates to orthopedic cut guides. Moreparticularly, the present invention relates to femoral cut guides andmethods for using the same.

2. Description of the Related Art

In a natural knee joint, the distal end of the femur articulates againstthe proximal end of the tibia. The knee joint is supported by variousligaments, including the posterior cruciate ligament (PCL) and theanterior cruciate ligament (ACL). These ligaments stabilize the kneejoint and cooperate to control the complex movements of the knee jointduring flexion and extension. The PCL, in particular, originates at thedistal femur and attaches to the posterior side of the proximal tibia toresist posterior translation of the tibia relative to the femur.

When the natural knee joint becomes damaged, a knee arthroplastyprocedure may be performed to resect the distal femur and/or theproximal tibia and to replace with resected bones with prostheticcomponents that are designed to simulate articulation of the naturalknee joint. It may also be necessary during the knee arthroplastyprocedure to sacrifice certain ligaments of the knee joint, such as thePCL. In those cases, the prosthetic knee components may also be designedto simulate the behavior of the sacrificed ligament. For example, if thePCL is sacrificed, the prosthetic femoral component and the prosthetictibial component may be stabilized posteriorly to resist posteriortranslation of the prosthetic tibial component relative to theprosthetic femoral component.

SUMMARY

The present disclosure provides a femoral cut guide for preparing adistal femur to receive a prosthetic femoral component of a kneeimplant. The prosthetic femoral component includes a central box. Thefemoral cut guide replicates the size and shape of the prostheticfemoral component, such that the femoral cut guide may serve as a trialor provisional component used to reduce and test the prepared knee jointbefore implanting the final prosthetic femoral component. The femoralcut guide includes a detachable box cut guide for preparing the distalfemur to receive the central box of the prosthetic femoral component.

According to an embodiment of the present invention, a femoral cut guideis provided for preparing a distal femur to receive a prosthetic femoralcomponent. The prosthetic femoral component includes a firstarticulating surface and an opposing first bone-contacting surface thatrests against the distal femur, the first bone-contacting surfaceincluding a first anterior portion, a first distal portion, and a firstposterior portion. The prosthetic femoral component further includes abox that projects proximally from the first distal portion of the firstbone-contacting surface. The femoral cut guide includes a body having asecond articulating surface that is shaped to replicate the firstarticulating surface and a second bone-contacting surface that is shapedto replicate the first bone-contacting surface, the secondbone-contacting surface including a second anterior portion, a seconddistal portion, and a second posterior portion. The femoral cut guidealso includes a box cut guide removably coupled to the body, the box cutguide including a reference surface located in a cut plane, thereference surface located proximally of the second distal portion of thesecond bone-contacting surface when the box cut guide is coupled to thebody, whereby the reference surface of the box cut guide guides acutting tool in the cut plane to remove bone from the distal femur so asto accommodate the box when the prosthetic femoral component is securedto the distal femur.

According to another embodiment of the present invention, a femoral cutguide is provided for preparing a distal femur to receive a prostheticfemoral component. The prosthetic femoral component includes a firstarticulating surface and an opposing first bone-contacting surface thatrests against the distal femur, the prosthetic femoral component furtherincluding a central box that projects proximally from the firstbone-contacting surface. The femoral cut guide includes a body having asecond articulating surface that is shaped to replicate the firstarticulating surface and a second bone-contacting surface that is shapedto replicate the first bone-contacting surface, the body including amedial side and a lateral side that define a central openingtherebetween. The femoral cut guide also includes a box cut guideremovably coupled to the body, the box cut guide including at least oneelongate guide slot that is sized to receive a cutting tool therein, theelongate guide slot extending from the medial side to the lateral sideof the body across the central opening in the body when the box cutguide is coupled to the body, whereby the box cut guide guides thecutting tool through the elongate guide slot and across the centralopening in the body to remove bone from the distal femur so as toaccommodate the central box when the prosthetic femoral component issecured to the distal femur.

According to yet another embodiment of the present invention, a methodis provided for preparing a distal femur to receive a prosthetic femoralcomponent, the prosthetic femoral component including a firstarticulating surface, an opposing first bone-contacting surface, and abox that projects proximally from the first bone-contacting surface to atop surface. The method includes the steps of: providing a body having asecond articulating surface that is shaped to replicate the firstarticulating surface and a second bone-contacting surface that is shapedto replicate the first bone-contacting surface; positioning the secondbone-contacting surface of the body against the distal femur; attachinga box cut guide to the body, the box cut guide including a referencesurface located in a cut plane; guiding a cutting tool across thereference surface of the box cut guide to prepare a resected surface ofthe distal femur, the resected surface of the distal femur located inthe cut plane; removing the body from the distal femur; and positioningthe first bone-contacting surface of the prosthetic femoral componentagainst the distal femur with the top surface of the box bordering theresected surface of the distal femur.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and advantages of this invention,and the manner of attaining them, will become more apparent and theinvention itself will be better understood by reference to the followingdescription of embodiments of the invention taken in conjunction withthe accompanying drawings, wherein:

FIG. 1 is a medial elevational view of a posterior-stabilized kneeimplant in a flexed position, the knee implant including a prostheticfemoral component secured to a distal femur and a prosthetic tibialcomponent;

FIG. 2 is a posterior perspective view of the prosthetic femoralcomponent of FIG. 1;

FIG. 3 is an exploded perspective view of an exemplary femoral cut guideof the present invention, the femoral cut guide including a removablebox cut guide and a removable posterior cut guide;

FIG. 4 is a perspective view of the box cut guide of FIG. 3;

FIG. 5 is an anterior perspective view of the posterior cut guide ofFIG. 3;

FIG. 6 is an exploded perspective view of another exemplary femoral cutguide of the present invention;

FIG. 7A is an exploded perspective view of yet another exemplary femoralcut guide of the present invention;

FIG. 7B is an assembled perspective view of the femoral cut guide ofFIG. 7A;

FIG. 8A is an exploded perspective view of still yet another exemplaryfemoral cut guide of the present invention;

FIG. 8B is an assembled perspective view of the femoral cut guide ofFIG. 8A;

FIG. 9A is an exploded perspective view a trial trochlear component foruse in conjunction with the femoral cut guides of the present invention;

FIG. 9B is an assembled perspective view of the trial trochlearcomponent and the femoral cut guide of FIG. 9A;

FIG. 10 is a medial elevational view of a cruciate-retaining kneeimplant in an extended position, the knee implant including a prostheticfemoral component secured to a distal femur;

FIG. 11 is a posterior perspective view of the prosthetic femoralcomponent of FIG. 10; and

FIG. 12 is an exploded perspective view of still yet another exemplaryfemoral cut guide of the present invention, the femoral cut guideincluding a box cut guide.

Corresponding reference characters indicate corresponding partsthroughout the several views. The exemplifications set out hereinillustrate exemplary embodiments of the invention and suchexemplifications are not to be construed as limiting the scope of theinvention in any manner.

DETAILED DESCRIPTION

FIGS. 1 and 2 illustrate a posterior-stabilized knee implant 100. Kneeimplant 100 includes prosthetic femoral component 102 configured toattach to a patient's distal femur 200 and prosthetic tibial component104 configured to attach to a patient's proximal tibia (not shown).

Prosthetic femoral component 102 of knee implant 100 includesarticulating surface 106 that articulates against prosthetic tibialcomponent 104, as shown in FIG. 1, and an opposing bone-contactingsurface 108 that rests against the patient's resected distal femur 200.Bone-contacting surface 108 of prosthetic femoral component 102 includesanterior portion 110, anterior chamfer portion 112, distal portion 114,posterior chamfer portion 116, and posterior portion 118.

Distal femur 200 includes corresponding resected surfaces that areshaped to receive bone-contacting surface 108 of prosthetic femoralcomponent 102. Specifically, distal femur 200 includes anterior resectedsurface 210 that is shaped to receive anterior portion 110 ofbone-contacting surface 108, anterior chamfer resected surface 212 thatis shaped to receive anterior chamfer portion 112 of bone-contactingsurface 108, distal resected surface 214 that is shaped to receivedistal portion 114 of bone-contacting surface 108, posterior chamferresected surface 216 that is shaped to receive posterior chamfer portion116 of bone-contacting surface 108, and posterior resected surface 218that is shaped to receive posterior portion 118 of bone-contactingsurface 108.

Also, prosthetic femoral component 102 of knee implant 100 includesmedial and lateral condyles 120, 122. Between medial and lateralcondyles 120, 122, prosthetic femoral component 102 includes box 124that defines a central opening 126. As shown in FIGS. 1 and 2, sidesurfaces 124 b of box 124 project proximally from distal portion 114 ofbone-contacting surface 108, with top surface 124 a of box 124 extendingposteriorly from anterior chamfer portion 112 toward posterior portion118 of bone-contacting surface 108. Box 124 may include anteriorprojection 129 having top surface 129 a and side surfaces 129 b, asshown in FIGS. 1 and 2. Also, between medial and lateral condyles 120,122, prosthetic femoral component 102 includes cam 128.

Prosthetic tibial component 104 of knee implant 100 includesarticulating surface 130 that articulates against prosthetic femoralcomponent 102, as shown in FIG. 1. Prosthetic tibial component 104 alsoincludes spine 132 that extends proximally from articulating surface130. When the patient's knee joint is extended, spine 132 is receivedfreely within opening 126 of box 124 of prosthetic femoral component102. When the patient's knee joint is flexed, as shown in FIG. 1, spine132 abuts cam 128 of prosthetic femoral component 102 to resistposterior translation of prosthetic tibial component 104 relative toprosthetic femoral component 102.

Referring to FIG. 3, femoral cut guide 12 is provided to prepare thepatient's distal femur to receive a prosthetic femoral component, suchas the posteriorly-stabilized prosthetic femoral component 102 of FIGS.1 and 2. More particularly, femoral cut guide 12 is provided to removebone from distal femur 200 to accommodate box 124 and anteriorprojection 129 of prosthetic femoral component 102 of FIGS. 1 and 2.

As shown by comparing FIGS. 2 and 3, femoral cut guide 12 of the presentinvention is substantially identical in size and shape to prostheticfemoral component 102 of knee implant 100. For example, femoral cutguide 12 may include articulating surface 16 that is substantiallyidentical in size and shape to articulating surface 106 of prostheticfemoral component 102, medial and lateral condyles 20, 22, that aresubstantially identical in size and shape to medial and lateral condyles120, 122, of prosthetic femoral component 102, and cam 28 that issubstantially identical in size and shape to cam 128 of prostheticfemoral component 102. Also, femoral cut guide 12 may includebone-contacting surface 18 that is substantially identical in size andshape to bone-contacting surface 108 of prosthetic femoral component102, such that bone-contacting surface 18 includes anterior portion 18a, anterior chamfer portion 18 b, distal portion 18 c, posterior chamferportion 18 d, and posterior portion 18 e. Therefore, in addition toguiding cutting of the patient's distal femur 200, femoral cut guide 12may serve as a trial or provisional component used to reduce and testthe prepared knee joint before implanting the final prosthetic femoralcomponent 102.

Before mounting femoral cut guide 12 onto the patient's distal femur 200(FIG. 1), a surgeon may first ream the patient's intramedullary canal(not shown). The prepared intramedullary canal may be used as a guide toreference various tools and cut guides throughout the knee arthroplastyprocedure.

Next, the surgeon may attach one or more preliminary cut guides to thepatient's distal femur 200 to make any preliminary resections. Forexample, one or more preliminary cut guides may be attached to thepatient's distal femur 200 to prepare anterior resected surface 210 thatwill later receive anterior portion 110 of prosthetic femoral component102, anterior chamfer resected surface 212 that will later receiveanterior chamfer portion 112 of prosthetic femoral component 102, distalresected surface 214 that will later receive distal portion 114 ofprosthetic femoral component 102, posterior chamfer resected surface 216that will later receive posterior chamfer portion 116 of prostheticfemoral component 102, and posterior resected surface 218 that willlater receive posterior portion 118 of prosthetic femoral component 102.Suitable preliminary cut guides include the “5-in-1 Femoral Saw Guide”and the “4-in-1 Femoral Cutting Guide,” both of which are available fromZimmer, Inc. of Warsaw, Ind.

The surgeon may make any necessary adjustments to the size and/orlocation of femoral cut guide 12 before anchoring femoral cut guide 12in place. For example, the surgeon may ensure that anterior portion 18a, anterior chamfer portion 18 b, distal portion 18 c, posterior chamferportion 18 d, and posterior portion 18 e of bone-contacting surface 18of femoral cut guide 12 rest properly against anterior resected surface210, anterior chamfer resected surface 212, distal resected surface 214,posterior chamfer resected surface 216, and posterior resected surface218 of distal femur 200, respectively. Also, the surgeon may ensure thatfemoral cut guide 12 is centered medially/laterally on the patient'sdistal femur 200 and that femoral cut guide 12 properly spans thepatient's distal femur 200. The surgeon may also guide femoral cut guide12 into place on the patient's distal femur 200 by referencing thepatient's intramedullary canal (not shown). Because femoral cut guide 12is substantially identical in size and shape to prosthetic femoralcomponent 102, the location of femoral cut guide 12 on the patient'sdistal femur 200 will correspond to the location of prosthetic femoralcomponent 102 on the patient's distal femur 200 (FIGS. 1 and 2). Iffemoral cut guide 12 does not properly fit the patient's bone, thesurgeon may select a different size of femoral cut guide 12, which willcorrespond to a different size of prosthetic femoral component 102. Ifnecessary, the surgeon may also re-cut the patient's distal femur 200.

Then, the surgeon may anchor femoral cut guide 12 to the patient'sdistal femur 200. As shown in FIG. 3, femoral cut guide 12 includesapertures 50, 52, that are sized to receive bone screws and/or pins foranchoring femoral cut guide 12 to the patient's distal femur 200. Beforemaking any cuts using femoral cut guide 12, the surgeon may use femoralcut guide 12 as a trial or provisional component to reduce and test thepartially-prepared knee joint before implanting the final prostheticfemoral component 102 (FIGS. 1 and 2).

With femoral cut guide 12 secured in place, the surgeon may prepare thepatient's distal femur 200 to receive box 124 and anterior projection129 of prosthetic femoral component (FIGS. 1 and 2). The order of thefollowing resection steps using femoral cut guide 12 may be varied.

Femoral cut guide 12 includes a detachable box cut guide 70, as shown inFIGS. 3 and 4. Box cut guide 70 defines box guide slot 72. Although theillustrated box cut guide 70 includes a reference surface that defines acaptured guide slot 72, it is also within the scope of the presentinvention that a single reference surface of box cut guide 70 may definean exposed or non-captured guide slot 72. When box cut guide 70 isattached to femoral cut guide 12, box guide slot 72 in box cut guide 70corresponds to and partially overlaps box guide slot 60 in femoral cutguide 12. Box cut guide 70 may include a textured surface 71 or handles(not shown) to improve the surgeon's ability to grip and manipulate boxcut guide 70.

In operation, the surgeon may insert a reciprocating or oscillating sawblade (not shown) into box guide slot 72 and drag the blade along plane72 a of box cut guide 70 (which corresponds to plane 60 a of femoral cutguide 12) to prepare the surface of the patient's distal femur 200 thatwill later receive box 124 of prosthetic femoral component 102 (FIGS. 1and 2). Like box 124 of prosthetic femoral component 102 (FIGS. 1 and2), planes 60 a, 72 a (FIG. 3) extend in an anterior/posteriordirection. More particularly, planes 60 a, 72 a, extend in ananterior/posterior direction from anterior chamfer portion 18 b toposterior portion 18 e of bone-contacting surface 18 of femoral cutguide 12.

Box cut guide 70 may be removably attached to femoral cut guide 12 and,optionally, to the patient's bone using one or more suitable fasteners.In the illustrated embodiment of FIG. 3, box cut guide 70 includes atleast one screw 74 that extends through aperture 75 in box cut guide 70,through aperture 76 in femoral cut guide 12, and into the patient'sbone. Box cut guide 70 also includes one leg 66 that extends into bore68 of femoral cut guide 12 to prevent box cut guide 70 from rotatingfreely relative to femoral cut guide 12.

In the illustrated embodiment of FIG. 6, box cut guide 70′ includes pins78′ that extend through apertures 76′ in femoral cut guide 12′ and intothe patient's bone. The two pins 78′ cooperate to prevent box cut guide70′ from rotating freely relative to femoral cut guide 12′.

In the illustrated embodiment of FIGS. 7A and 7B, box cut guide 70″includes screw 74″ that extends through aperture 75″ in box cut guide70″, through aperture 76″ in femoral cut guide 12″, and into thepatient's bone. Box cut guide 70″ also includes two legs 66″ that extendinto bores 68″ of femoral cut guide 12″ to prevent box cut guide 70″from rotating freely relative to femoral cut guide 12″. Unlike pins 78′of box cut guide 70′ (FIG. 6), legs 66″ of box cut guide 70″ may bereceived within femoral cut guide 12″ without extending into thepatient's bone. As shown in FIG. 7A, legs 66″ are located on either sideof screw 74″ in box cut guide 70″, and bores 68″ are located on eitherside of aperture 76″ in femoral cut guide 12″.

In the illustrated embodiment of FIGS. 8A and 8B, box cut guide 70′″includes screw 74′″ that extends through aperture 75′″ in box cut guide70′″, through a non-circular aperture 76′″ in femoral cut guide 12′″,and into the patient's bone. Box cut guide 70′″ also includes anon-circular leg 66′″ surrounding screw 74′″ that extends into thenon-circular aperture 76′″ along with screw 74′″ to prevent box cutguide 70′″ from rotating freely relative to femoral cut guide 12′″.

According to an exemplary embodiment of the present invention, box cutguide 70 is selectively rotatable relative to femoral cut guide 12, suchthat box cut guide 70 may be used with both right-leg and left-legfemoral cut guides 12. For example, in the illustrated embodiment ofFIG. 3, box cut guide 70 may be rotated 180 degrees about leg 66 andcoupled to a right-leg femoral cut guide that is the mirror image of theleft-leg femoral cut guide 12 shown in FIG. 3. Box cut guide 70 includesan additional aperture 75 a for screw 74 that may be used instead ofaperture 75 when rotated to accommodate the other leg. In theillustrated embodiment of FIG. 6, box cut guide 70′ may be rotated 180degrees about an axis located between pins 78′, and pins 78′ may beinserted into the opposite apertures 76′ of a right-leg femoral cutguide. For example, the proximal-most pin 78′ that is shown beinginserted into the proximal-most aperture 76′ of the left-leg femoral cutguide 12′ may be inserted into the other, distal-most aperture of aright-leg femoral cut guide. In the illustrated embodiment of FIG. 7A,box cut guide 70″ may be rotated 180 degrees about screw 74″ and legs66″ may be inserted into the opposite apertures 68″ of a right-legfemoral cut guide. In the illustrated embodiment of FIG. 8A, box cutguide 70′″ may be rotated 180 degrees about leg 66′″.

Femoral cut guide 12 further includes a detachable projection cut guide80, as shown in FIGS. 3 and 5. Projection cut guide 80 definesprojection guide slot 82. Although the illustrated projection cut guide80 includes a reference surface that defines a captured guide slot 82,it is also within the scope of the present invention that a singlereference surface of projection cut guide 80 may define an exposed ornon-captured guide slot 82. When projection cut guide 80 is attached tofemoral cut guide 12, projection guide slot 82 in projection cut guide80 corresponds to and partially overlaps projection guide slot 62 infemoral cut guide 12. Projection cut guide 80 may include a texturedsurface 81 or handles (not shown) to improve the surgeon's ability togrip and manipulate projection cut guide 80.

In operation, the surgeon may insert a reciprocating or oscillating sawblade (not shown) into projection guide slot 82 and drag the blade alongplane 82 a of projection cut guide 80 (which corresponds to plane 62 aof femoral cut guide 12) to prepare the surface of the patient's femurthat will later receive anterior projection 129 of prosthetic femoralcomponent 102 (FIGS. 1 and 2). Like anterior projection 129 ofprosthetic femoral component 102 (FIGS. 1 and 2), planes 62 a, 82 a(FIG. 3) extend in a proximal, slightly anterior direction. Moreparticularly, planes 62 a, 82 a, extend in a proximal, slightly anteriordirection from distal portion 18 c to anterior portion 18 a ofbone-contacting surface 18 of femoral cut guide 12.

Projection cut guide 80 may be removably attached to femoral cut guide12 and, optionally, to the patient's bone using one or more suitablefasteners. In the illustrated embodiment of FIGS. 3 and 5, projectioncut guide 80 includes at least one screw 84 that extends throughaperture 85 in projection cut guide 80, through apertures 86 in femoralcut guide 12, and into the patient's bone. Projection cut guide 80 alsoincludes legs 87 that extend into apertures 86 of femoral cut guide 12to prevent projection cut guide 80 from rotating freely relative tofemoral cut guide 12.

In the illustrated embodiment of FIG. 6, projection cut guide 80′includes one or more pins 88′ instead of screws 84 (FIG. 3). Pins 88′extend through apertures 86′ in femoral cut guide 12′ and into thepatient's bone. The two pins 88′ cooperate to prevent projection cutguide 80′ from rotating freely relative to femoral cut guide 12′.

To complete the resections of distal femur 200 (FIG. 1), the surgeon maydetach box cut guide 70 and projection cut guide 80 from femoral cutguide 12. Then, the surgeon may drag a reciprocating or oscillating sawblade (not shown) along side walls 90, 92, of femoral cut guide 12. Thesurgeon may attempt to insert the blade only to the depth of planes 60a, 62 a. As shown in FIG. 3, planes 60 a, 62 a, define an obtuse angle αtherebetween.

The bone removed from distal femur 200 using femoral cut guide 12 willaccommodate box 124 and projection 129 of prosthetic femoral component102 (FIGS. 1 and 2). More particularly, the bone removed from distalfemur 200 along plane 60 a will accommodate top surface 124 a of box124, the bone removed from distal femur 200 along plane 62 a willaccommodate top surface 129 a of projection 129, and the bone removedfrom distal femur 200 along side walls 90, 92, will accommodate sidesurfaces 124 b of box 124 and side surfaces 129 b of projection 129.

With box cut guide 70 and projection cut guide 80 removed, the surgeonmay use femoral cut guide 12 as a trial or provisional component toreduce and test the prepared knee joint before implanting the finalprosthetic femoral component 102 (FIGS. 1 and 2). In certainembodiments, the surgeon may couple a trial trochlear component 94, asshown in FIGS. 9A and 9B, to femoral cut guide 12 in opening 96 betweenside walls 90, 92. Trial trochlear component 94 may include protrusions98 that are sized for receipt into corresponding recesses 46, 48, offemoral cut guide 12 (FIG. 3) to couple the components together. Whenassembled, the surgeon may verify proper articulation of femoral cutguide 12 against the patient's adjacent patella and tibia (not shown).

Advantageously, the ability to test the prepared knee joint usingfemoral cut guide 12 allows the surgeon to visualize the location of thefinal prosthetic femoral component 102 (FIGS. 1 and 2) before cuttingthe patient's bone to receive box 124 and projection 129 of prostheticfemoral component 102. Also, the ability to test the prepared knee jointusing femoral cut guide 12 eliminates the additional steps of removingfemoral cut guide 12 and replacing it with a separate trial component.Moreover, the removable box cut guide 70 and projection cut guide 80allow a single femoral cut guide 12 to be used for multiple cuts.

According to an exemplary embodiment of the present invention, femoralcut guide 12 may be able to receive box cut guides 70 and/or projectioncut guides 80 of various shapes and sizes. In this embodiment, a singlefemoral cut guide 12 may be used to prepare distal femur 200 (FIG. 1) toreceive various prosthetic femoral components, such as the NexGen® LPSFemoral Component and the NexGen® Legacy® LCCK Femoral Component, bothof which are available from Zimmer, Inc. of Warsaw, Ind. To preparedistal femur 200 to receive the LPS Femoral Component (which may besubstantially similar to prosthetic femoral component 102 of FIG. 2),the illustrated box cut guide 70 may be used with femoral cut guide 12.The LCCK Femoral Component may have a taller, more proximally orientedbox than the LPS Femoral Component. To prepare distal femur 200 toreceive the taller, more proximally oriented box of the LCCK FemoralComponent, a second box cut guide (not shown) may be provided with amore proximally oriented guide slot than the first box cut guide 70 andmay be used with the same femoral cut guide 12 as the first box cutguide 70. Advantageously, the surgeon may make intraoperative changeswithout having to remove and replace femoral cut guide 12.

According to another exemplary embodiment of the present invention, boxcut guides 70 and/or projection cut guides 80 may be adjustably coupledto femoral cut guide 12. For example, the depth and/or orientation ofeach box cut guide 70 and each projection cut guide 80 may be adjustedrelative to femoral cut guide 12. Returning to the previous example,femoral cut guide 12 may have a first set of holes for receiving box cutguide 70 to accommodate the LPS Femoral Component and a second set ofholes for receiving box cut guide 70 in a more proximal position toaccommodate the taller, more proximally oriented box of the LCCK FemoralComponent. Advantageously, the surgeon may make intraoperative changeswithout having to remove and replace femoral cut guide 12.

Referring next to FIGS. 10 and 11, a cruciate-retaining knee implant 300is provided including prosthetic femoral component 302 configured toattach to a patient's distal femur 200. Prosthetic femoral component 302may be similar to the NexGen® Complete Knee Solution Cruciate-Retaining(CR) Femoral Component, which is available from Zimmer, Inc. of Warsaw,Ind.

Prosthetic femoral component 302 of FIGS. 10 and 11 may include certainfeatures that are similar to prosthetic femoral component 102 of FIGS. 1and 2, except as described below. Prosthetic femoral component 302 ofknee implant 300 includes articulating surface 306 and an opposingbone-contacting surface 308 that rests against the patient's resecteddistal femur 200. Bone-contacting surface 308 of prosthetic femoralcomponent 302 includes anterior portion 310, anterior chamfer portion312, distal portion 314, posterior chamfer portion 316, and posteriorportion 318.

Prosthetic femoral component 302 of knee implant 300 also includesmedial and lateral condyles 320, 322. Between medial and lateralcondyles 320, 322, prosthetic femoral component 302 includes anteriorbox 329. As shown in FIGS. 10 and 11, side surfaces 329 b of anteriorbox 329 project proximally from anterior chamfer portion 312 and distalportion 314 of bone-contacting surface 308, with top surface 329 a ofanterior box 329 extending posteriorly and distally from anteriorportion 310 toward distal portion 314 of bone-contacting surface 308.When implanted on distal femur 200, anterior box 329 may extendproximally into the patient's bone to support and stabilize prostheticfemoral component 302.

Referring to FIG. 12, femoral cut guide 412 is provided to prepare thepatient's distal femur to receive the cruciate-retaining prostheticfemoral component 302 of FIGS. 10 and 11. More particularly, femoral cutguide 412 is provided to remove bone from distal femur 200 toaccommodate anterior box 329 of prosthetic femoral component 302.Femoral cut guide 412 of FIG. 12 may include certain features that aresimilar to femoral cut guide 12 of FIG. 3, femoral cut guide 12′ of FIG.6, femoral cut guide 12″ of FIG. 7A, and/or femoral cut guide 12′″ ofFIG. 8A, with like reference numerals indicating like elements, exceptas described below.

As shown by comparing FIGS. 11 and 12, femoral cut guide 412 of thepresent invention is substantially identical in size and shape toprosthetic femoral component 302 of knee implant 300. For example,femoral cut guide 412 may include articulating surface 416 that issubstantially identical in size and shape to articulating surface 306 ofprosthetic femoral component 302, medial and lateral condyles 420, 422,that are substantially identical in size and shape to medial and lateralcondyles 320, 322, of prosthetic femoral component 302, andbone-contacting surface 418 that is substantially identical in size andshape to bone-contacting surface 308 of prosthetic femoral component302.

Femoral cut guide 412 also includes a detachable box cut guide 480, asshown in FIG. 12, which may be substantially similar or identical toprojection cut guide 80 of FIG. 3. Box cut guide 480 defines box guideslot 482. Although the illustrated box cut guide 480 includes areference surface that defines a captured guide slot 482, it is alsowithin the scope of the present invention that a single referencesurface of box cut guide 480 may define an exposed or non-captured guideslot 482. When box cut guide 480 is attached to femoral cut guide 412,box guide slot 482 in box cut guide 480 corresponds to and partiallyoverlaps box guide slot 462 in femoral cut guide 412. Box cut guide 480may include a textured surface 481 or handles (not shown) to improve thesurgeon's ability to grip and manipulate box cut guide 480. Inoperation, the surgeon may insert a reciprocating or oscillating sawblade (not shown) into box guide slot 482 to prepare the surface of thepatient's femur that will later receive anterior box 329 of prostheticfemoral component 302 (FIGS. 10 and 11).

Box cut guide 480 may be removably attached to femoral cut guide 412and, optionally, to the patient's bone using one or more suitablefasteners. In the illustrated embodiment of FIG. 12, box cut guide 480includes at least one screw 484 that extends through aperture 485 in boxcut guide 480, through apertures 486 in femoral cut guide 412, and intothe patient's bone. Box cut guide 480 also includes legs 487 that extendinto apertures 486 of femoral cut guide 412 to prevent box cut guide 480from rotating freely relative to femoral cut guide 412.

Femoral cut guide 412 further includes laterally spaced slots 490, 492.To complete the resections of distal femur 200 (FIG. 10), the surgeonmay drag a reciprocating or oscillating saw blade (not shown) throughslots 490, 492, of femoral cut guide 412 (which are similar in locationand orientation to side walls 90, 92, of femoral cut guide 12).

The bone removed from distal femur 200 using femoral cut guide 412 willaccommodate anterior box 329 of prosthetic femoral component 302 (FIG.10). More particularly, the bone removed from distal femur 200 using boxcut guide 480 will accommodate top surface 329 a of anterior box 329 andthe bone removed from distal femur 200 along slots 490, 492, willaccommodate side surfaces 329 b of anterior box 329.

With box cut guide 480 removed, the surgeon may use femoral cut guide412 as a trial or provisional component to reduce and test the preparedknee joint before implanting prosthetic femoral component 302 (FIGS. 10and 11). Advantageously, the ability to test the prepared knee jointusing femoral cut guide 412 allows the surgeon to visualize the locationof the final prosthetic femoral component 302 (FIGS. 10 and 11) beforecutting the patient's bone to receive anterior box 329 of prostheticfemoral component 302. Also, the ability to test the prepared knee jointusing femoral cut guide 412 eliminates the additional steps of removingfemoral cut guide 412 and replacing it with a separate trial component.Moreover, the removable box cut guide 480 allows a single femoral cutguide 412 to be used for multiple cuts.

While this invention has been described as having exemplary designs, thepresent invention can be further modified within the spirit and scope ofthis disclosure. This application is therefore intended to cover anyvariations, uses, or adaptations of the invention using its generalprinciples. Further, this application is intended to cover suchdepartures from the present disclosure as come within known or customarypractice in the art to which this invention pertains and which fallwithin the limits of the appended claims.

1. A femoral cut guide for preparing a distal femur to receive aprosthetic femoral component, the prosthetic femoral component includinga first articulating surface and an opposing first bone-contactingsurface that rests against the distal femur, the first bone-contactingsurface including a first anterior portion, a first distal portion, anda first posterior portion, the prosthetic femoral component furtherincluding a box that projects proximally from the first distal portionof the first bone-contacting surface, the femoral cut guide comprising:a body having a second articulating surface that is shaped to replicatethe first articulating surface and a second bone-contacting surface thatis shaped to replicate the first bone-contacting surface, the secondbone-contacting surface including a second anterior portion, a seconddistal portion, and a second posterior portion; and a box cut guideremovably coupled to the body, the box cut guide including a referencesurface located in a cut plane, the reference surface located proximallyof the second distal portion of the second bone-contacting surface whenthe box cut guide is coupled to the body, whereby the reference surfaceof the box cut guide guides a cutting tool in the cut plane to removebone from the distal femur so as to accommodate the box when theprosthetic femoral component is secured to the distal femur.
 2. Thefemoral cut guide of claim 1, wherein a top surface of the box extendsbetween the first anterior portion and the first posterior portion ofthe first bone-contacting surface, the cut plane intersecting the secondanterior portion and the second posterior portion of the secondbone-contacting surface, whereby the reference surface of the box cutguide guides the cutting tool in the cut plane to remove bone from thedistal femur so as to accommodate the top surface of the box when theprosthetic femoral component is secured to the distal femur.
 3. Thefemoral cut guide of claim 1, wherein a top surface of the box extendsbetween the first anterior portion and the first distal portion of thefirst bone-contacting surface, the cut plane intersecting the secondanterior portion and the second distal portion of the secondbone-contacting surface, whereby the reference surface of the box cutguide guides the cutting tool in the cut plane to remove bone from thedistal femur so as to accommodate the top surface of the box when theprosthetic femoral component is secured to the distal femur.
 4. Thefemoral cut guide of claim 1, wherein the reference surface of the boxcut guide defines a guide slot that is sized to receive the cutting tooltherein, the cut plane extending through the guide slot.
 5. The femoralcut guide of claim 1, wherein the box cut guide is removably coupled toan anterior side of the body.
 6. The femoral cut guide of claim 1,wherein the second anterior portion of the second bone-contactingsurface extends substantially parallel to the second posterior portionof the second bone-contacting surface, the cut plane extendingtransversely to both the second anterior portion and the secondposterior portion of the second bone-contacting surface.
 7. The femoralcut guide of claim 1, wherein the cut plane extends substantiallyparallel to the second distal portion of the second bone-contactingsurface.
 8. The femoral cut guide of claim 1, wherein the box cut guideis rotatable 180 degrees about an axis between a first orientation and asecond orientation, the box cut guide including at least one boss thatengages the body to retain the box cut guide in one of the first andsecond orientations.
 9. The femoral cut guide of claim 1, furthercomprising a second cut guide removably coupled to the body at aseparate location from the box cut guide, the second cut guide includinga second reference surface that is located in a second cut plane. 10.The femoral cut guide of claim 9, wherein the second cut plane of thesecond cut guide intersects the cut plane of the box cut guide to definean obtuse angle therebetween.
 11. A femoral cut guide for preparing adistal femur to receive a prosthetic femoral component, the prostheticfemoral component including a first articulating surface and an opposingfirst bone-contacting surface that rests against the distal femur, theprosthetic femoral component further including a central box thatprojects proximally from the first bone-contacting surface, the femoralcut guide comprising: a body having a second articulating surface thatis shaped to replicate the first articulating surface and a secondbone-contacting surface that is shaped to replicate the firstbone-contacting surface, the body including a medial side and a lateralside that define a central opening therebetween; and a box cut guideremovably coupled to the body, the box cut guide including at least oneelongate guide slot that is sized to receive a cutting tool therein, theelongate guide slot extending from the medial side to the lateral sideof the body across the central opening in the body when the box cutguide is coupled to the body, whereby the box cut guide guides thecutting tool through the elongate guide slot and across the centralopening in the body to remove bone from the distal femur so as toaccommodate the central box when the prosthetic femoral component issecured to the distal femur.
 12. The femoral cut guide of claim 11,wherein each of the medial side and the lateral side of the bodyincludes a planar reference surface that borders the central opening,each of the planar reference surfaces configured to guide the cuttingtool through the central opening in a direction substantiallyperpendicular to the elongate guide slot.
 13. The femoral cut guide ofclaim 11, wherein the box cut guide is rotatable 180 degrees about anaxis between a first orientation and a second orientation, the box cutguide including at least one boss that engages the body to retain thebox cut guide in one of the first and second orientations.
 14. Thefemoral cut guide of claim 11, further comprising a second cut guideremovably coupled to the body at a separate location from the box cutguide, the second cut guide including a second elongate guide slot thatis sized to receive the cutting tool therein.
 15. The femoral cut guideof claim 14, wherein the second guide slot of the second cut guide andthe guide slot of the box cut guide define an obtuse angle therebetween.16. The femoral cut guide of claim 11, wherein each of the first andsecond bone-contacting surfaces includes an anterior portion, a distalportion, an anterior chamfer portion that extends obtusely from theanterior and distal portions, a posterior portion, and a posteriorchamfer portion that extends obtusely from the distal and posteriorportions.
 17. A method of preparing a distal femur to receive aprosthetic femoral component, the prosthetic femoral component includinga first articulating surface, an opposing first bone-contacting surface,and a box that projects proximally from the first bone-contactingsurface to a top surface, the method comprising the steps of: providinga body having a second articulating surface that is shaped to replicatethe first articulating surface and a second bone-contacting surface thatis shaped to replicate the first bone-contacting surface; positioningthe second bone-contacting surface of the body against the distal femur;attaching a box cut guide to the body, the box cut guide including areference surface located in a cut plane; guiding a cutting tool acrossthe reference surface of the box cut guide to prepare a resected surfaceof the distal femur, the resected surface of the distal femur located inthe cut plane; removing the body from the distal femur; and positioningthe first bone-contacting surface of the prosthetic femoral componentagainst the distal femur with the top surface of the box bordering theresected surface of the distal femur.
 18. The method of claim 17,wherein the reference surface of the box cut guide defines a guide slot,the guiding step comprising guiding the cutting tool through the guideslot.
 19. The method of claim 17, further comprising the step ofevaluating articulation between the body and an adjacent tibialcomponent when the body is positioned against the distal femur.
 20. Themethod of claim 17, further comprising the steps of: attaching a secondcut guide to the body, the second cut guide including a second referencesurface located in a second cut plane; and guiding the cutting toolacross the second reference surface of the second cut guide to prepare asecond resected surface of the distal femur, the second resected surfaceof the distal femur located in the second cut plane.
 21. The method ofclaim 20, wherein positioning the first bone-contacting surface of theprosthetic femoral component against the distal femur further comprisespositioning a projection from the box against the second resectedsurface of the distal femur.